Occluding anatomical structures

ABSTRACT

An elongate resilient tube of a mesh of shape memory alloy is used to therapeutically occlude an opening in body tissue. The tube is compressible so that it can be delivered to the opening in the body within a catheter. The tube self-expands as it is released from the catheter to contiguously form, sequentially an outer perimeter structure and an inner perimeter structure disposed within the outer perimeter structure to conformingly engage an inner side of the outer perimeter structure, a plate shaped structure, and a flexible connector between them. J-shaped hooks extend from the perimeter structure to flexibly engage tissue of the body opening without piercing the tissue.

FIELD OF THE DISCLOSURE

The disclosure relates to a system and method for occluding anatomicalstructures, and more particularly to a catheter delivered flexibleself-anchoring cover for an internal body opening.

BACKGROUND OF THE DISCLOSURE

Occlusion devices are used to occlude or cover extra anatomicalanomalies or malformations in the body which include for exampleappendages and aneurysms which can critically alter the normalfunctioning of a vessel or organ in the body. These anatomicalstructures can create a risk of clot formation which can lead to strokeor other serious or life threatening conditions. The risk can be greatlyreduced by plugging or covering an opening into the structure.

SUMMARY OF THE DISCLOSURE

In accordance with the disclosure, a device for occluding an appendageinside a living body forming an elongate passage and having an openentrance and a hollow interior, comprises at least one elongateresilient tube formed of a mesh of shape memory alloy, the tubecompressible to be delivered to the appendage within a catheter, the atleast one tube self-expanding as the tube is released from the catheterto contiguously form, sequentially: an outer perimeter structure that iselongate on a side portion of the outer perimeter structure to be sizedand dimensioned to flexibly conform to a longitudinal anatomy of aninterior surface of the appendage extending along a longitudinal axis ofthe appendage when the device is deployed within the appendage; an innerperimeter structure sized and dimensioned along an elongate contact areato flexibly and conformingly contact an interior of the outer perimeterstructure to thereby mutually conform to the interior surface of theappendage together with the outer perimeter structure when the device isdeployed within the appendage, the inner perimeter structure forming asnap fit with the outer perimeter structure when the device is deployedwithin the appendage due to a shape memory effect of folding of thedevice, wherein the inner perimeter structure frictionally engages theouter perimeter structure along the elongate contact area to therebyresist displacement of the outer perimeter structure along thelongitudinal axis of the appendage, the inner perimeter structure andthe outer perimeter structure together forming a single double-walledperimeter structure defining a hollow interior; a plurality of hookseach affixed to the outer bell-shaped structure to extend away from theouter bell-shaped structure, forming a barb having J-shape, and forminga sharp free end profile at an end of the barb.

In variations thereof, the plurality of hooks define rows encircling aperimeter of the device; the hook having a height of 1.0 mm+/−0.25 mm asmeasured from a curved end of the J-shape to the sharp free end profile;the hook having a length of 1.5 mm+/−0.25 mm as measured from a surfaceof the outer perimeter structure from which the barb extends to thesharp free end profile of the barb; the hook can be pulled straight whenthe elongate resilient tube is returned to the catheter, and the hookwill re-form the J-shape after the elongate resilient tube is againreleased from the catheter; at least two hooks are formed from a singlewire bent to form a U-shape before the wire is affixed to the outerbell-shaped structure; a curved portion of the U-shape is folded uponitself when the single wire is affixed to the outer bell-shapedstructure; and/or the at least one elongate resilient tube includesfirst and second elongate resilient tubes, the second elongate resilienttube disposed within the first elongate resilient tube.

In a further variation thereof, a method for occluding an appendageinside a living body, comprising delivering the device by a catheter andpositioning the device in the appendage to engage the plurality of hookswith body tissue.

In variations of the method, each of the plurality of hooks are sized topierce the body tissue without passing through an external wall of theappendage; the appendage is the left atrial appendage (LAA); and/or theat least one elongate resilient tube is a single elongate resilienttube, which is partially involuted to form inner and outer sleeves thatform the double-walled bell-shaped structure, tubular connector, andplate-shaped structure.

In another variation thereof, the device further includes a tubularconnector having a diameter substantially smaller than the double-walledperimeter structure and the opening of the appendage, the tubularconnector extending away from an apex of the double-walled perimeterstructure and through the hollow perimeter interior.

In a further embodiment of the disclosure, a device for occluding anappendage inside a living body forming an elongate passage and having anopen entrance and a hollow interior comprises at least one elongateresilient tube formed of a mesh of shape memory alloy, the tubecompressible to be delivered to the appendage within a catheter, the atleast one tube self-expanding as the tube is released from the catheterto contiguously form, sequentially: an outer bell-shaped structure thatis elongate on a side portion of the bell-shape to be sized anddimensioned to flexibly conform to a longitudinal anatomy of an interiorsurface of the appendage extending along a longitudinal axis of theappendage when the device is deployed within the appendage; an innerbell-shaped structure sized and dimensioned along an elongate contactarea to flexibly and conformingly contact an interior of the outerbell-shaped structure to thereby mutually conform to the interiorsurface of the appendage together with the outer bell-shaped structurewhen the device is deployed within the appendage, the inner bell-shapedstructure forming a snap fit with the outer bell-shaped structure whenthe device is deployed within the appendage due to a shape memory effectof folding of the device, wherein the inner bell-shaped structurefrictionally engages the outer bell-shaped structure along the elongatecontact area to thereby resist displacement of the outer bell-shapedstructure along the longitudinal axis of the appendage, the innerbell-shaped structure and the outer bell-shaped structure togetherforming a single double-walled bell-shaped structure defining a hollowbell interior; a tubular connector having a diameter substantiallysmaller than the double-walled bell-shaped structure and the opening ofthe appendage, the tubular connector extending away from an apex of thedouble-walled bell-shaped structure and through the hollow bellinterior; and a plurality of hooks each affixed to the outer bell-shapedstructure to extend away from the outer bell-shaped structure, forming abarb having J-shape, and forming a sharp free end profile at an end ofthe barb.

In variations thereof, the plurality of hooks define rows encircling aperimeter of the device; the hook having a height of 1.0 mm+/−0.25 mm asmeasured from a curved end of the J-shape to the sharp free end profile;and/or the hook having a length of 1.5 mm+/−0.25 mm as measured from asurface of the outer perimeter structure from which the barb extends tothe sharp free end profile of the barb.

In other variations thereof, the hook can be pulled straight when theelongate resilient tube is returned to the catheter, and the hook willre-form the J-shape after the elongate resilient tube is again releasedfrom the catheter; at least two hooks are formed from a single wire bentto form a U-shape before the wire is affixed to the outer bell-shapedstructure; and/or a curved portion of the U-shape is folded upon itselfwhen the single wire is affixed to the outer bell-shaped structure.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present disclosure, and theattendant advantages and features thereof, will be more readilyunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings wherein:

FIG. 1 depicts a side view of an occlusion device of the disclosure;

FIG. 2A depicts a cactus type left atrial appendage (LAA);

FIG. 2B depicts a windsock type LAA;

FIG. 2C depicts a cauliflower type LAA;

FIG. 2D depicts a chicken wing type LAA;

FIG. 2E depicts a wall or septum within the body having an opening orperforation;

FIG. 3 depicts the device of FIG. 1 secured in place within an LAA;

FIG. 4 depicts the device of FIG. 1 beginning to emerge from a catheter;

FIG. 5 depicts the device of FIG. 1, continuing to emerge and beginningto form an outer bell-shape structure;

FIG. 6 depicts the device of FIG. 1, continuing to emerge and form theouter bell-shape structure;

FIG. 7 depicts the device of FIG. 1, continuing to emerge and completingformation of the outer bell-shape structure;

FIG. 8 depicts the device of FIG. 1, continuing to emerge and beginningto form an inner bell-shape structure;

FIG. 9 depicts the device of FIG. 1, continuing to emerge and completingformation of the inner bell-shape structure;

FIG. 10 depicts the device of FIG. 1, continuing to emerge and forming aconnector portion, and beginning to form a cover structure;

FIGS. 11-12 depict the device of FIG. 1, continuing to emerge andcontinuing to form the cover structure;

FIG. 13 depicts the device of FIG. 1, fully emerged from the catheterand fully formed;

FIG. 14 depicts a perspective view of the device of FIG. 13;

FIG. 15 depicts an attachment mechanism between the device and adeployment cable of the catheter;

FIG. 16 depicts retrieval of the device of FIG. 1, the cover returningto a balloon-like shape as it is pulled into the catheter;

FIG. 17 depicts retrieval of the device of FIG. 1, the cover fullywithdrawn into the catheter;

FIG. 18 depicts retrieval of the device of FIG. 1, the inner bell-shapewithdrawn;

FIG. 19-21 depicts retrieval of the device of FIG. 1, the outerbell-shape in progressive stages of being withdrawn;

FIG. 22 depicts all but a distal end of the device of FIG. 1 withdrawninto the catheter;

FIG. 23 depicts an isometric view of a set of hooks of the disclosure;

FIG. 24 depicts a side view of the hooks of FIG. 23;

FIG. 25 depicts a top view of a device of the disclosure, the dual plateconfiguration including a filtering membrane;

FIG. 26 depicts the device of FIG. 25, detailing a threaded connector ofthe disclosure;

FIG. 27 is a detailed view of hooks of the disclosure, attached usingsutures to an outer bell-shaped structure of a device of the disclosure;

FIG. 28 depicts a cross-section of the device of FIG. 1, in place toocclude a perforation in a septum;

FIG. 29 depicts an alternative anchor configuration including anadditional plate-shaped structure;

FIG. 30 depicts an alternative anchor configuration including a balloonshaped structure;

FIG. 31 depicts an alternative anchor configuration including a reversebell-shaped structure;

FIG. 32A diagrammatically depicts a single layer tubular structure usedto form a device of the disclosure;

FIG. 32B depicts a dual layer structure which can be formed by turning alonger single layer tubular structure inside out, or by nesting twotubular structures;

FIG. 32C diagrammatically depicts a dual layer structure forming adevice of the disclosure;

FIG. 33A depicts a dual layer structure formed of an inside tubularstructure that has a different braid or mesh structure than an outertubular structure;

FIG. 33B depicts the inside and outside tubular structures of FIG. 33Ain a mutually reversed location;

FIG. 34 depicts a perimeter structure of an anchor of the disclosureincluding a U-shaped wire forming two hooked ends that is affixed to theperimeter structure;

FIG. 35 depicts an alternative view of the hooks of FIG. 34;

FIG. 36 depicts the U-shaped wire of FIG. 34 prior to being assembledinto and affixed into the perimeter structure, the U-shaped curved endfolded onto itself;

FIG. 37 depicts the U-shaped wire of FIG. 34, each end cut to apredetermined length and formed with J-shaped hooks at each free end;

FIG. 37A depicts a detail of a J-shaped hook of FIG. 37;

FIG. 38 depicts the U-shaped wire of FIG. 37, the U-shaped curved endfolded onto itself;

FIG. 39 depicts a detailed view of the hooks of FIG. 34, together withsutures used to affix the U-shaped wire and formed hooks to theperimeter structure;

FIG. 40 depicts a ruler measuring a height of the hooks of FIG. 39;

FIG. 41 depicts a ruler measuring a length of the hooks of FIG. 39;

FIG. 42 depicts a measuring tool to validate a height, length, and shapeof the hooks of FIG. 39;

FIG. 43 depicts a back side of a tool assembly for cutting the U-shapedwire of FIG. 36 to a predetermined length, once the U-shaped wire isaffixed to the perimeter structure;

FIG. 44 depicts a front side of the tool assembly of FIG. 43;

FIG. 45 depicts the U-shaped wires of FIG. 36 assembled onto and affixedto the perimeter structure of an anchor of the disclosure, a free end ofa U-shaped wire inserted between cutting blades of the tool assembly ofFIG. 43, in preparation for cutting the free end to a predeterminedlength with respect to a surface of the perimeter structure; and

FIG. 46 depicts a mandrel positioned to facilitate and control formationof the J-shape of FIG. 34.

DETAILED DESCRIPTION OF THE DISCLOSURE

As required, detailed embodiments are disclosed herein; however, it isto be understood that the disclosed embodiments are merely examples andthat the systems and methods described below can be embodied in variousforms. Therefore, specific structural and functional details disclosedherein are not to be interpreted as limiting, but merely as a basis forthe claims and as a representative basis for teaching one skilled in theart to variously employ the present subject matter in virtually anyappropriately detailed structure and function. Further, the terms andphrases used herein are not intended to be limiting, but rather, toprovide an understandable description of the concepts.

The terms “a” or “an”, as used herein, are defined as one or more thanone. The term plurality, as used herein, is defined as two or more thantwo. The term another, as used herein, is defined as at least a secondor more. The terms “including” and “having,” as used herein, are definedas comprising (i.e., open language). The term “coupled,” as used herein,is defined as “connected,” although not necessarily directly, and notnecessarily mechanically.

With reference to FIGS. 1-3, a device 100 of the disclosure includes ananchor 120 sized to conformingly engage interior sidewalls of amalformed or anomalous anatomical structure within the body (hereinafterthe ‘anatomical structure’), and a cover 160 sized to occlude or overliean opening into the structure. Devices 100 of the disclosure can be usedto occlude any opening of the body. Examples are shown in FIGS. 2A-2D,diagrammatically illustrating various known types of left atrialappendages (LAAs), and FIG. 2E illustrating any type of tissue wallhaving an undesired opening.

FIG. 3 illustrates a ‘windsock’ type LAA 302 of a human heart 300, incross-section, closed off or occluded with device 100. Additionallyshown in part are the left atrium 306, and the left superior pulmonaryvein 308. It may be seen that an outer anchor sidewall forming aperimeter structure, or outer bell-shape 124 is conforming to aconvoluted geometry of the interior surface 304 of the LAA. It mayfurther be seen that cover 160 conforms to the surface of anatomy, inthis example the interior of atrium 306, and is eventually covered overby body tissue.

Device 100 is attached to a deployment cable 180 (visible in FIG. 15),and is inserted into a catheter 182 for deployment or retrieval. In theexample of the LAA, the catheter is passed through a vein in the leg,and passes into the left atrium through a transseptal puncture of theinteratrial septum, or by other known method. A pigtail catheter can beused to reduce a possibility of LAA perforation, and a preloadeddelivery catheter can be advanced over the pigtail into the LAA, aswould be understood within the art. The preloaded delivery catheter isadvanced into the tip of an access sheath, and is deployed by firstpushing the device into the sheath. Then, while the sheath remains inplace at the mouth of the LAA, device 100 is pushed out using cable 180which is connected to device 100. A final position can be confirmed withTransesophageal Echocardiography (TEE), intracardiac echocardiography(ICE), fluoroscopy, or any other known method.

A catheter can likewise be used to access any other body structure intowhich device 100 is to be deployed or retrieved. Device 100 isconstructed as a mesh of resilient expandable material. In theembodiment shown, the mesh is formed from woven strands of memory wire.Alternatively, device 100 can be formed by stamping apertures in a sheetof such material. Within the catheter, device 100 forms an elongatedtubular structure that is held in a compressed form. In an embodiment,the mesh is formed from a polymeric material, and can be woven fromstrands; stamped from a sheet which then fused along an edge to form atube; or is molded into the form described herein. The tube can bebraided or knitted, and is molded in specific shapes disclosed herein inorder to be able to be compressed, delivered inside the body, andreleased to resume the molded shape.

Whether stamped or formed as a wire mesh, the resilient expandablematerial can be a shape memory metal or alloy such as nitinol, althoughanother material that is super-elastic, resilient, has a shape memoryeffect to resume a pre-formed shape, and is durable and biocompatible.Specific shape memory materials that can be used includecopper-aluminum-nickel, and nickel titanium alloys, although othermaterials having similar characteristics may be used, which are eitherknown or are to be hereinafter developed. The material can be acombination of a shape memory metal and a polymeric material, whereinthe polymeric fibers are interspaced within the strands of Nitinol, asshown in the illustrations. Additionally, cladded materials can be used,for example wherein the Nitinol is cladded on the outside with platinum,gold, another biocompatible noble metal, or any other passive materials.The disclosed device 100 shapes are made by forcing the braid or theknit into a mold corresponding to the desired final shape, and thenapplying a prescribed heat for a predetermined time, in accordance withthe requirements of the material selected, to heat set the mold shape.

In various embodiments, the tubular structure 102 (FIG. 32A) of device100 is open at each end, or is closed at one or both ends. In theembodiment illustrated, the woven material is closed at each end. At adistal end 132 which emerges from the catheter into the body first, thewoven material is gathered into a crimp 122, although other forms ofclosure can be carried out, including using adhesive, brazing,soldering, fusing, sewing, or a clip or other fastener, for example. Ata proximal end of device 100, material is gathered and attached to aconnector 170, so that device 100 can be releasably attached todeployment cable 180. Attachment can be by any means, including athreaded connection or twist-lock connection, for example, and can befabricated using a biocompatible metal or plastic material, for example.By gathering and crimping distal end 132, a potential for piercing ofbody tissue is reduced. In an embodiment, connector 170 includes afemale threaded portion connected to device 100, and a mating malethreaded portion at the end of cable 180. Connector 170 enables cable180 to push device 100 out of the sheath and into the anatomicalstructure where device 100 can be released by unthreading connector 170.If needed, cable 180 can be rethreaded to connector 170, whereupondevice 100 can be retrieved from the body by pulling cable 180.

Device 100 is pushed by deployment cable 180 through catheter 182.Accordingly, the material of device 100 must be sufficiently stiff toresist collapsing and allowing cable 180 to advance past device 100. Asportions of device 100 are released from catheter 182, the memoryfunction of the shaped memory metal causes the formation ofpredetermined shapes, as shown in the Figures and as described herein.

In FIG. 4, crimp 122 at distal end 132 emerges from catheter 180 first.It may be seen that the woven structure of device 100 is compressedtogether to enable device 100 to fit within the catheter. In FIGS. 5 and6, device 100 self-expands based upon the resilient spring-like natureof the shape memory alloy. Initially, this self-expansion forms aballoon-like structure, as the mesh is permitted to expand upon releasefrom the catheter. In FIG. 7, an edge appears, and a general outline ofan outer bell-shape 124 of anchor 120 becomes evident. As can be seen inFIG. 7, the bell-shaped structure is hollow, and is formed with a singlewall. In FIG. 8, a lower edge 130 reverses upon itself, and an innerperimeter structure, in this example forming a corresponding bell-shape126, forms within the outer bell-shape 124. In FIG. 9, it may be seenthat inner bell-shape 126 abuts, and reinforces, outer bell shape 124,forming the hollow, double-walled bell shape of anchor 120. Innerbell-shape 126 conformingly engages an inner side of outer bell-shape124, and thereby locks outer bell-shape into conforming engagement withbody tissue of the anatomical structure.

In FIG. 10, the structure of cover 160 begins to emerge from catheter182, and to expand. A tubular connector 128 extends between a distal end132 of device 100, at an apex of inner bell-shape 126, to cover 160. InFIG. 11, it may be seen that cover 160, as with anchor 120, is formed ofdual layers, which initially appear as a balloon-like structure duringexpansion. In FIG. 12, distal and proximal cover surfaces 162 and 164,respectively, begin to form. In FIG. 13, cover 160 has taken its finaldual layer, dual plate-shape configuration. FIG. 15 is a perspectiveview, in which it may be seen that cover 160 has a distal surface,adjacent anchor 120, that is substantially planar, although it can becurved to conform to particular anatomy to be occluded. Other shapes canbe formed which are best suited for a particular anatomical structure tobe covered. Proximal cover surface 164 can lie spaced apart from distalcover surface 162, for example by forming a depression 168, so that itcan resiliently press outer cover edge 166 firmly against body tissuewhile distal cover surface conforms to body tissue.

In an embodiment, at least proximal cover surface 164 is coated with atissue growth factor, to promote integration of cover 160 into the body,further securing device 100 within the body, and further reducing apossibility of clot formation. It may be advantageous to coat all ofdevice 100 with such growth factor, or to integrate the growth factorinto a coating of the shape memory material of device 100, where it maybe released slowly over time. Other substances can be used to coat partor all of device 100, for example including a blood thinner, antibiotic,drug, or other therapeutic substance. Device 100 may be covered with aflexible fabric, for example a polymeric fabric such as polyethyleneterephthalate (PET) or other biocompatible material. This can beadvantageous if it is desired to filter particles from entering orleaving the anatomical structure which are smaller than the openings inthe mesh of device 100. Similarly, a nano-material can be used to coverdevice 100.

Additionally or alternatively, nanomaterials such as platinum or gold oranother passive material can be used to coat the occluding device. Insuch coatings, each individual wire is coated using vapor depositiontechnology or nano-layering technology, so that individual wires orfibers in device 100 are coated with a thin or ultrathin layer ofmaterial.

In the embodiment of FIGS. 25-26, a polymeric filtering fabric filter178 is inserted between proximal and distal cover surfaces 162, 164, andprovides further protection from migration of clots or particles fromwithin the anatomical structure to the blood stream. Filter 178 can beheld in place by being attached to connector 170, or it can be suturedor adhered in place at least until deployment, when it is maintained inposition by being constrained between surfaces 162 and 164. Filter 178can be fabricated from any biocompatible material that is compressibleduring deployment, including for example PET fabric, and which has adesired mesh or pore size.

In FIGS. 14-15, deployment cable 180 is visible as a rod of coiled wire,although any known construction can be used. Cable 180 can be rotatedaxially to unthread or otherwise disconnect cable mating connectorportion 170, attached to deployment cable 180, from a device matingconnector portion 170.

In FIG. 15, device 100 begins to be recaptured or retrieved intocatheter 182, causing some distortion in proximal cover surface 164.Retrieval can be carried out for repositioning device 100 within thesame procedure, or for removing device 100 after an extended period oftime. In FIG. 16, a collapsing pressure is applied by an end of catheter182, and cover 160 is stretched to once again form a balloon shape,which has entered the catheter in FIG. 17. In FIG. 18, inner bell-shape126 is pulled away from outer bell-shape 124, and is drawn into catheter182. In FIG. 19, inner bell-shape 126 has inverted, forming a balloonshape together with outer bell-shape 124. In FIGS. 21 and 22, innerbell-shape 126 is drawn into catheter 182, and finally, in FIG. 22,outer bell-shape 124 is drawn into catheter 182, where only clip 122 isvisible. Device 100 can be fully removed from the body by continuing towithdraw deployment cable 180 from catheter 182.

Additionally visible in the Figures, and with reference to FIGS. 23-24,are hooks 140, attached to anchor 120. It should be understood thatanchor 120 can securely attach to body tissue by pressing outwardsagainst inner walls of the anatomical structure into which it has beeninserted, and by resiliently conforming to the interior surface, asshown and described herein. Accordingly, hooks 140 are optional, but canbe used where it is desired to provide an additional safeguard againstdevice 100 becoming dislodged or embolized. Hooks 140 include a barbportion 142, which projects at an angle from the surface of outerbell-shape 124 of anchor 120, whereby hooks 140 can insert into bodytissue as anchor 120 expands to its final conforming shape within thebody.

A flattened portion 144 is woven into or otherwise attached to outerbell-shape 124, for example using sutures 176, as shown in FIGS. 14 and27 (omitted in certain other figures, for clarity), to maintain aparticular angular disposition with respect to a surface of device 100after deployment. Where anchor 120 is formed as a stamping, barbs 142can be bent to form the required angle. Barbs 142 are resilientlyattached to flattened portion 144, so that they can be folded to lieagainst flattened portion 144 during deployment and retrieval of device100 through catheter 182. The particular shape of the hook structure inFIGS. 23 and 24 is one example of how hooks can be formed and attachedto a mesh material of device 100. Other shapes and styles of hooks orbarbs are known in the art, and can be used with device 100 of thedisclosure. Additionally, the number of hooks 140, if used at all, canbe varied in accordance with the requirements of the particulardeployment. The attaching sutures can be made with Polyethyleneterephthalate (PET), Polypropylene, or Polytetrafluoroethylene (PTFE),for example.

Anchor 120 of the disclosure, due to its bell shape, can compress to asmall proportion of its deployed diameter, enabling it to conform to,and securely attach to, a wide range of anatomical structure diameters.In particular, anchor 120 forms a bell shape with elongated sidewalls,wherein the bell is open at the bottom, facilitating close andundistorted tracking of the elongated sidewalls to the geometry of bodytissue in an interior of the anatomical structure. The wide range ofcompression further ensures that it can maintain engagement withinternal sidewalls despite substantial motion of body tissues,particularly within the heart. For occluding an LLA, for example, outerbell-shape 124 can have a diameter of as small as about 18 mm, up toabout 36 mm, for typical anatomy. While each device can accommodate awide range of variation in a diameter of the body tissue, for an optimalfit, outer bell-shape 124 can be provided in sizes at increments of 2mm, for example 18 mm, 20 mm, 22 mm, 24 mm, 26 mm, 28 mm, 30 mm, 32 mm,34 mm and 36 mm. Inside bell-shape 126 has a diameter of about 2 mm lessthan outside bell-shape 124, when device 100 is not pressed against bodytissue, so would be sized at 16 mm, 18 mm, 20 mm, 22 mm, 24 mm, 26 mm,28 mm, 30 mm, 32 mm and 34 mm.

In addition, the wide range of compression enables it to conform tosubstantial changes in the internal diameter of the anatomical structureover time. The wide range of resiliency, and large surface area oftissue contact, enable device 100 to be atraumatic, for embodimentswithout hooks 140. The extended contact area of device 100 furthereliminates a need for oversizing in order to form a tight fit againstbody tissue, thereby avoiding tearing of body tissue, particularly inview of continuous movement of the body tissue, as in the heart. Furtherdue to the wide range of compression, a reduced range of sizes fordevice 100 need to be maintained on-hand. The expanded diameter size ofdevice 100 is determined by the range of diameters of anatomicalstructures to be occluded. For use in occluding LAAs, device 100 can beprovided in one or more expanded diameters of between 21 and 33 mm, forexample, and using, for example, a 9-Fr to 14-Fr catheter.

Cover 160, being formed of two layers of mesh, is also resilient, andcan compress and deform to a substantial extent, to conform to theanatomy external to, or at the entrance to, the anatomical structure. Inparticular, distal cover surface 162 can contact and follow a tissuesurface shape, while proximal cover surface 164, which is separated fromdistal cover surface 162, can maintain its shape while exerting acompressive force against distal cover surface 162.

Because device 100 is formed as a fine mesh, for example having openingsof less than 1 mm, it can tightly seal against the body, and function asa filter immediately upon deployment, whether or not an overcoatingfabric is provided. In addition, the mesh structure contacts body tissuewith an even and diffuse application of pressure, improving grip withbody tissue, while reducing trauma. The aperture sizes is determined bythe pitch width and the pitch angle of the wires from which the mesh ofdevice 100 is formed. These factors can be predetermined to form a meshopening of a desired size, for example less than 1 mm, when the braidconstruction is completed. In this manner, the mesh is very compact,enabling retention of any clots inside the anatomical structure cavity.

By forming a separate anchor 120 and cover 160, device 100 enablesanchor 120 to independently compress and conform to a wide variety ofinternal structures, while cover 160, which is separated from anchor 120by tubular connector 128, can remain expanded to its fullest diameter,completely covering an opening to the anatomical structure. Moreover, astubular connector 128 is highly flexible, it can bend to enable cover160 to lie in close contact with body tissue outside of, or at anentrance to the anatomical structure, at an angle that is independent ofan angular disposition of anchor 120.

Outer bell-shape 124 and inner bell-shape 126 interact to form asnap-fit or locking button, which prevents displacement of device 100within the body. More particularly, and without being bound to aparticular theory, outer bell-shape 124 conformingly engages an interiorsurface of the anatomical structure while it is still in a very flexibledeformable balloon shape. When inner bell-shape 126 snaps into itsmemory shape, aligned within outer bell-shape 124, it locks the outerbell-shape 124 in this conformed configuration, by completing the shapememory inner-outer bell shape. Once the shape memory has been allowed toreform, it is resistant to further changes, particularly by displacementalong a longitudinal axis extending between a proximal end at connector170, and distal end 132, which would need to overcome the memory imposedshape. This prevents outer bell-shape 124 from rolling or otherwisemoving along a surface of body tissue. Additionally, the force appliedby inner bell-shape 126 against outer bell-shape 124 stiffens outerbell-shape 124 within its current conforming configuration, furtherresisting displacement of outer bell-shape 124 with respect to bodytissue.

When occluding an opening or gap 320 in a tissue wall 322, for exampleof the type shown in FIG. 2E, device 100 can be positioned with cover160 and anchor 120 on opposite sides of the wall, as shown in FIG. 28.Anchor 120 compresses by displacing lower edge 130 in a directiontowards distal end 132, causing cover 160 to compress against oppositeside of wall 320.

While the inventors have found that anchor 120 is advantageously abell-shaped structure connected to and cooperative with a plate-shapedwhich remains in place in the left atrium. However, device 100 can beconfigured for other areas of the body where the bell-shaped structurecan have an alternate configuration which is better adapted to differentanatomical geometry than the left atrium. For example, in other areas ofthe body, other structures can be formed, such as another plate-shapedstructure 120A (FIG. 29), a balloon shape 120B (FIG. 30) which isgenerally spherical, ovoid, or pear shape, for example; oralternatively, a reverse bell 120C (FIG. 31) can be formed.

The inventor has further found that a dual layer structure 102A, 102B,102C (FIG. 32B-33) of device 100 provides for improved pushabilitythrough the catheter and into the body, improving a resistance totwisting and further maintaining a desired post-expansion shape. Duallayers can provide for improved radial strength, and provide increasedsurface density for desired blocking or occlusion of anatomy afterdeployment, and as well as an improved scaffold for tissue growth.

FIG. 32A illustrates a single layer tubular structure 102, and FIG. 32Billustrates tubular structure 102A which has been folded in on itself toform a dual layer tubular structure 102A. This double layer structure isthen formed and the desired post-expansion shape is formed as otherwisedescribed elsewhere herein, as shown in FIG. 32C.

The diameter or thickness of the wires forming the mesh of device 100can be selected based upon the patient size, the dimensions of theimplant site and target anatomy, and the strength required. Thedisclosure can be carried out with any wire thickness which will yield adevice 100 having the properties shown and described herein. In oneembodiment not intended to be limiting, the wires are of a very thinsize suitable for 144 carrier medical braider, or heavier wires suitablefor a 72 carrier braider. In another embodiment, the inner layer andouter layer are formed with different braider carrier types, for examplea relatively thicker 72 carrier for the inner layer, and a thinner 144carrier for the outer layer. in this manner, the outside layer of 144carrier braids provides relatively greater metal coverage due to thethinner wires more densely woven, while the inside layer of 72 braidsprovides relatively greater axial and radial strength to maintain thedesired form shapes, for example cover 160 and anchor 120, and tomaintain the shapes in a desired location.

FIG. 33A illustrates, diagrammatically, an outer layer 104 which has alower braid count, and an inner layer 106 with a higher braid count, thetwo layers joined at their ends. The resulting dual layer structure isthen formed into the desired shape as described herein (e.g. as shown inFIG. 32C). FIG. 33B depicts the layers reversed, with the lower braidcount 106 on the outside. The dual layer configurations described hereinare otherwise formed and used as described herein.

Dissimilar braid sizes for the inside and outside surfaces can be joinedat seams using any known method, including for example welding, brazing,soldering, weaving stamping pinching, crimping, braiding, or othermethod. When both layers are made from the same braid size, the innerlayer can be formed by partially involuting or folding a portion of thebraided material inside the other, or turning inside-out, a part of abraided tube, for example half of a tube. The interaction of the duallayers of braided or woven metals facilitates the various propertiesdescribed herein, including enabling the expanded formation ofstructures having a desired variable depth and width to accommodate awide variety of anatomical structures which need to be closed. Examplesof such anatomical structures are found in a variety of anatomicalindications like Neurological procedures, Cardiovascular procedures,Peripheral procedures, and procedures involving other systems.

With reference to FIGS. 34-35, device 100 includes hooks 140A which areaffixed to anchor 120 via flexible filaments or sutures 176 as describedelsewhere herein. As can be seen in FIGS. 34-35, two hook barbs 142A areformed from the ends of a single strand of drawn, stamped or otherwiseformed longitudinal filament or wire 146 which is bent. In the exampleillustrated in FIGS. 34-38, barbs 142A form at least approximately a Jshape, and wire 146 generally forms a U-shape. As depicted, wire 146 canbe woven into the weave of anchor 120, after which it is further securedby sutures 176.

In accordance with the disclosure, providing a separate hook 140/140A-Benables different hook sizes and/or shapes to be used with a givenanchor 120 and anchor 120 size. Further, hooks 140/140A-B can befabricated from a different material than that of anchor 120, and cantherefore have any desired attributes relative to the material of anchor120, such as flexibility, shape memory, resilience, strength, sharpness,and other characteristics described herein. In one example embodiment,hooks 140/140A-B are formed from platinum coated nitinol having athickness of 0.0085 inches, although thinner or thicker wire of the sameor differing material can be used which provides sufficient strength andresiliency for the applications described herein.

As can be seen in FIG. 35, wire 146 of hook 140B forms a generallyU-shape as in FIG. 34, and barbs 142A are not yet formed. However, itmay be seen that at fold 148, a base of the U-shape is folded over uponitself. Fold 148 can be formed before or after wire 146 is woven intoanchor 120, and can be attached via sutures 176 at various locations, tofurther secure wire 146 to anchor 120. Fold 148 provides additionalpoints at which wire 146 can be secured by sutures 176, and additionalprovides resistance to twisting of wire 146, so that barbs 142Aremaining extending away from a surface of anchor 120 at a desiredangle, as described further elsewhere herein. Barbs 142A can be cut andformed after wire 146 has been woven into and secured to anchor 120, asdescribed in further detail with respect to FIG. 41, below. Final shapesof hooks 140A, 140B, shown without anchor 120, are depicted in FIGS. 37and 38, respectively.

With reference to FIGS. 39-41, it may be seen that barbs 142A emergefrom the woven mesh of anchor 120 to complete the ‘J’ shape shown inFIGS. 34-38. In FIG. 40, a ruler is placed horizontally to lie against asurface of anchor 120 to measure a height of barb 142A which extendsfrom the bottom of the curved portion of barb 142A to a free end of barb142A, and in FIG. 41, the ruler is placed to extend vertically away fromthe surface of anchor 120 to measure a length of the barb 142A whichextends from a surface of anchor 120 to the free end of barb 142A.

Accurate measurement of the barbs 142/142A in the design and productionof devices 100 of the disclosure enables exploiting the close conformingnature of the double layer conforming contact of anchor 120 with the LAAinterior that is provided by the disclosure. More particularly, it isdesired to penetrate completely into the wall of the LAA with barb142/142A, without passing completely through the LAA wall, and moreparticularly, without endangering penetration of, or actuallypenetrating the left superior pulmonary vein 308, which passes closelyby or in contact with the LAA. The close conforming nature of devices100 of the disclosure provides additional control of an extent ofpenetration of barbs 142/142A, by limiting movement of the barb withbody tissue, which would otherwise be affected by the continuous motionof the heart, which would repeatedly urge any contacting device intovarying levels of contact with body tissue.

The disclosure thus addresses a limitation of the prior art, wherein ifa gap exists between a device and body tissue of the LAA at a locationof a barb, the barb would be urged into body tissue to varying extentsby the beating heart, hindering anchoring, and endangeringover-penetration. Moreover, the prior must choose a barb size that islong enough to cross any such gap, rending the barb too long if thedevice is moved closer to body tissue during beating of the heart.

As barbs 142/142A are held fully inserted into body tissue, a length,height, and shape can be chosen which optimizes penetration and contactof the barb with body tissue of the LAA, while minimizing a chance ofpenetration. Further, in accordance with the disclosure, duringdeployment, cover 160 interacts with bell-shaped portions 124/126 todraw cover 160 and the bell-shaped structure 124/126 towards each other,fully seating barbs 142/142A, while an extent of penetration is limitedby the close conforming contact of inner and outer bell-shaped portionsand the LAA, as described in detail elsewhere herein.

The inventors have found that an optimal penetration depth in adults,reflected in the length and height of barb 142/142A detailed herein,provides sufficient contact with the LAA for secure anchoring, whileminimizing risk of penetration. For substantially smaller or largeranatomy, these values can change accordingly. The J-shape of barbs 142Ais selected to penetrate vertically to an optimal extent, while enablingfurther penetration horizontally, obtaining the benefit of greatercontact with body tissue, without substantial risk of penetrating toodeeply, or piercing the LAA.

The inventors have found that for typical adults, the height and lengthdetailed herein are optimal for anchoring barb 142 within tissue of theLAA, without causing complete penetration of the LAA, while able tobridge gaps between the outer bell-shape of anchor 120 and body tissueof the LAA, for the various LAA tissue shapes, such as chicken wing,mushroom, and other shapes, some of which are shown as examples in FIGS.2A-2D.

Horizontal penetration length, and thus an overall height of barb 142Ais selected to ensure that even if barb 142A does not completelymaintain a J shape during penetration, the overall depth of penetrationwill not be excessive. The inventors have found an overall height fortypical adults of 1.0 mm+/−0.25 mm to be optimal for a barb 142A havinga length of 1.5 mm+/l 0.25 mm. These values can additionally vary basedupon the flexibility of barb 142A.

Flexibility of barb 142/142A (collectively barb 142) is furtherdetermined by using a material which has a shape memory, such as nitinoland the like. In an embodiment, hook 140/140A-B (collectively hook 140)are formed from Nitinol coated with platinum, which is secured to anchor120 by sutures, as shown in the drawings, or by welding, brazing,soldering, or any other means which is biocompatible and of sufficientstrength, and which will bind hook 140 until device 100 is secured bytissue ingrowth/overgrowth. Flexibility is additionally determined by across-sectional width and shape of hook 140 material. In an embodiment,hook 140 material has a round cross-section of round wire having adiameter of 0.085 inches. Shape memory is additionally enhanced by heatsetting the shape memory material, whereby the barbs can be straightenedand drawn back into the implantation catheter and then redeployed ifdesired, whereby barbs 142 will resume the original deployment shape.

A choice of material and cross-sectional shape and diameter are selectedto enable device 100 to be withdrawn into the sheath after barbs 142 areset, where the force to at least partially straighten barb 142 to enablewithdrawal is less than a force required to substantially tear bodytissue into which barb 142 is set, but sufficiently rigid to preventdisengagement due to any anticipated extent of heart tissue movement.

Referring now to FIGS. 43-45, a tool 404 for cutting wire, such asside-cutting snips as shown, or an end cutting nipper (not shown), ismounted to a base 406 so that a lower handle 408 is affixed to base 406,and an upper handle 410 is free to move. A vertical support 412 can beprovided to facilitate attachment of lower handle 408 to base 406.Cutting jaws 414 include angled blades, such that a cut edge of hooks140 and barb 142 end form a sharpened cut edge 150, as shown in FIG.37A. Sharp end 150 is thus shaped with a sharpened linear edge thatensures a small defined penetration into tissue of the LAA withoutcausing tearing. The cut edge additionally promotes a secure anchorwhile the heart is beating, until tissue growth prevents furthermovement of device 100. Likewise, sharp end 150 ensures readypenetration where the LAA has developed thickened or dense tissue.

A stop plate 416 forms a vertical wall 418 and one or more wire entryportals 418 through which each free end 420 (FIGS. 36 and 45) of hook140A can be passed. As shown in FIG. 45, hooks 140 are first affixed toanchor 120, and then cut to length with respect to the surface fromwhich the hook 140 emerges. This is carried out by passing one or bothof free ends 420 of an affixed hook 140 each through a portal 418 toemerge on an opposite side of the stop plate to lie between the cuttingjaws 414 of tool 404. The body of the anchor 120, for example outerbell-shape 124, is pressed against stop plate 416 to normalize each cutto a cut length corresponding to the height and width as measured inFIGS. 40-41, after bending to form the final shape (FIG. 46); however,stop plate eliminates the need to position a ruler and measure each cut.Stop plate 416 can be provided with portals 418 of different diametercorresponding to varying hook 140 diameters that may be used tomanufacturer various devices 100.

Portals 418 can be formed by drilling through stop plate, or by firstremoving a portion of stop plate 416, filing or otherwise forming one ormore grooves, then reattaching the removed plate to form precise portal418 diameters as needed, as can be seen in FIG. 43. Stop plate 416 canbe attached to base 406 and/or to vertical support 412, to ensure apredetermined gap exists between an anchor contacting face of stop plate416, and a mating cutting edge of cutter jaws 414, to achieve thedesired hook 140 length. If it is desired to have hooks 140 of differinglengths for a given device 100, a different tool 404 can be providedwith a different gap to cutter jaws 414, or an additional plate (notshown) with a predetermined thickness can be placed between stop plate416 and anchor 120. A view port 422 can be provided to visibly confirmthat the cutter jaws 414 are open for receiving ends 420 therebetween.

Base plate, stop plate, and vertical support can be mutually attached bythreaded fastener (as shown) or by adhesive, soldering, welding, clampsor other fastener, or any other suitably strong means which preventsmovement of the components over time which may interfere with accuratemeasurement between stop plate 416 and cutter jaws 414.

In FIG. 46, a mandrel 424 (shown in cross-section) is positioned againstan outer surface of anchor 120 from which hook 140 emerges, and hook 140is further bent to form the J-shape described herein. Mandrel 424 has adiameter selected to produce a hook 140 having a resulting J-shaped barb142 having the dimensions described herein.

For volume production, a measuring and quality control tool can be usedfor evaluating a height, length, and shape of barbs 142A, such asdimension checking tool 400 shown in FIG. 42. More particularly, aseries of cutout portions 402 are each provided with a predeterminedwidth and height. A cutout portion 402 having a target height and lengthfor a given product version is selected, and is positioned on top of theemerged and bent barb 142A, with the tool resting upon, and the open endof cutout portion 402 facing, the surface of anchor 120. For an idealfit, barb 142A contacts or nearly contacts all three sides of the cutoutportion, thereby enabling a quick simultaneous measurement of height,length, and shape. To further speed measurement, all remaining or unusedcutout portions 402 having unneeded dimensions can be masked off, forexample by tape or a cover.

All references cited herein are expressly incorporated by reference intheir entirety. It will be appreciated by persons skilled in the artthat the present disclosure is not limited to what has been particularlyshown and described herein above. In addition, unless mention was madeabove to the contrary, it should be noted that all of the accompanyingdrawings are not to scale. There are many different features to thepresent disclosure and it is contemplated that these features may beused together or separately. Thus, the disclosure should not be limitedto any particular combination of features or to a particular applicationof the disclosure. Further, it should be understood that variations andmodifications within the spirit and scope of the disclosure might occurto those skilled in the art to which the disclosure pertains.Accordingly, all expedient modifications readily attainable by oneversed in the art from the disclosure set forth herein that are withinthe scope and spirit of the present disclosure are to be included asfurther embodiments of the present disclosure.

Drawing References:   100 device 102/102A tubular structure 104 shapeouter layer 106 shape inner layer 120 anchor 122 crimp 124 outerbell-shape 126 inner bell-shape 128 tubular connector 130 lower edge 132distal end 140/140A-B hooks 142/142A hook barb 144/144A hook flattenedportion 146 wire 148 folded over U-shape 150 barb cut end 160 cover 162distal cover surface 164 proximal cover surface 166 outer cover edge 170connector 176 suture/hook attachment 178 filter 180 cable 180 deploymentcable 182 catheter 300 human heart 306 left atrium 308 left superiorpulmonary vein 340 LAA interior surface 400 dimension checking tool 402ruler 404 cutter 406 base 408 lower handle 410 upper handle 412 verticalsupport 414 cutter jaws 416 stop plate 418 stop plate portal 420 hookfree end 422 tool view port 424 mandrel

What is claimed is:
 1. A device for occluding an appendage inside aliving body forming an elongate passage and having an open entrance anda hollow interior, comprising: at least one elongate resilient tubeformed of a mesh of shape memory alloy, the tube compressible to bedelivered to the appendage within a catheter, the at least one tubeself-expanding as the tube is released from the catheter to contiguouslyform, sequentially: an outer perimeter structure that is elongate on aside portion of the outer perimeter structure to be sized anddimensioned to flexibly conform to a longitudinal anatomy of an interiorsurface of the appendage extending along a longitudinal axis of theappendage when the device is deployed within the appendage; an innerperimeter structure sized and dimensioned along an elongate contact areato flexibly and conformingly contact an interior of the outer perimeterstructure to thereby mutually conform to the interior surface of theappendage together with the outer perimeter structure when the device isdeployed within the appendage, the inner perimeter structure forming asnap fit with the outer perimeter structure when the device is deployedwithin the appendage due to a shape memory effect of folding of thedevice, wherein the inner perimeter structure frictionally engages theouter perimeter structure along the elongate contact area to therebyresist displacement of the outer perimeter structure along thelongitudinal axis of the appendage, the inner perimeter structure andthe outer perimeter structure together forming a single double-walledperimeter structure defining a hollow interior; a plurality of hookseach affixed to the outer bell-shaped structure to extend away from theouter perimeter structure, forming a barb having J-shape, and forming asharp free end profile at an end of the barb.
 2. The device of claim 1,the plurality of hooks defining rows encircling a perimeter of thedevice.
 3. The device of claim 1, the hook having a height of 1.0mm+/−0.25 mm as measured from a curved end of the J-shape to the sharpfree end profile.
 4. The device of claim 1, the hook having a length of1.5 mm+/−0.25 mm as measured from a surface of the outer perimeterstructure from which the barb extends to the sharp free end profile ofthe barb.
 5. The device of claim 1, wherein the hook can be pulledstraight when the elongate resilient tube is returned to the catheter,and the hook will re-form the J-shape after the elongate resilient tubeis again released from the catheter.
 6. The device of claim 1, whereinat least two hooks are formed from a single wire bent to form a U-shapebefore the wire is affixed to the outer bell-shaped structure.
 7. Thedevice of claim 6, wherein a curved portion of the U-shape is foldedupon itself when the single wire is affixed to the outer bell-shapedstructure.
 8. The device of claim 1, wherein the at least one elongateresilient tube includes first and second elongate resilient tubes, thesecond elongate resilient tube disposed within the first elongateresilient tube.
 9. A method for occluding an appendage inside a livingbody, comprising delivering by a catheter the device of claim 1, andpositioning the device in the appendage to engage the plurality of hookswith body tissue.
 10. The method of claim 9, wherein each of theplurality of hooks are sized to pierce the body tissue without passingthrough an external wall of the appendage.
 11. The method of claim 10,wherein the appendage is the left atrial appendage (LAA).
 12. The methodof claim 9, wherein the at least one elongate resilient tube is a singleelongate resilient tube, which is partially involuted to form inner andouter sleeves that form the double-walled bell-shaped structure, tubularconnector, and plate-shaped structure.
 13. The device of claim 1,further including a tubular connector having a diameter substantiallysmaller than the double-walled perimeter structure and the opening ofthe appendage, the tubular connector extending away from an apex of thedouble-walled perimeter structure and through the hollow perimeterinterior.
 14. A device for occluding an appendage inside a living bodyforming an elongate passage and having an open entrance and a hollowinterior, comprising: at least one elongate resilient tube formed of amesh of shape memory alloy, the tube compressible to be delivered to theappendage within a catheter, the at least one tube self-expanding as thetube is released from the catheter to contiguously form, sequentially:an outer bell-shaped structure that is elongate on a side portion of thebell-shape to be sized and dimensioned to flexibly conform to alongitudinal anatomy of an interior surface of the appendage extendingalong a longitudinal axis of the appendage when the device is deployedwithin the appendage; an inner bell-shaped structure sized anddimensioned along an elongate contact area to flexibly and conforminglycontact an interior of the outer bell-shaped structure to therebymutually conform to the interior surface of the appendage together withthe outer bell-shaped structure when the device is deployed within theappendage, the inner bell-shaped structure forming a snap fit with theouter bell-shaped structure when the device is deployed within theappendage due to a shape memory effect of folding of the device, whereinthe inner bell-shaped structure frictionally engages the outerbell-shaped structure along the elongate contact area to thereby resistdisplacement of the outer bell-shaped structure along the longitudinalaxis of the appendage, the inner bell-shaped structure and the outerbell-shaped structure together forming a single double-walledbell-shaped structure defining a hollow bell interior; a tubularconnector having a diameter substantially smaller than the double-walledbell-shaped structure and the opening of the appendage, the tubularconnector extending away from an apex of the double-walled bell-shapedstructure and through the hollow bell interior; and a plurality of hookseach affixed to the outer bell-shaped structure to extend away from theouter bell-shaped structure, forming a barb having J-shape, and forminga sharp free end profile at an end of the barb.
 15. The device of claim14, the plurality of hooks defining rows encircling a perimeter of thedevice.
 16. The device of claim 14, the hook having a height of 1.0mm+/−0.25 mm as measured from a curved end of the J-shape to the sharpfree end profile.
 17. The device of claim 14, the hook having a lengthof 1.5 mm+/−0.25 mm as measured from a surface of the outer perimeterstructure from which the barb extends to the sharp free end profile ofthe barb.
 18. The device of claim 14, wherein the hook can be pulledstraight when the elongate resilient tube is returned to the catheter,and the hook will re-form the J-shape after the elongate resilient tubeis again released from the catheter.
 19. The device of claim 14, whereinat least two hooks are formed from a single wire bent to form a U-shapebefore the wire is affixed to the outer bell-shaped structure.
 20. Thedevice of claim 14, wherein a curved portion of the U-shape is foldedupon itself when the single wire is affixed to the outer bell-shapedstructure.